Electronic devices can contain a number of electronic components that are electrically and mechanically coupled to one another. For example, many devices employing integrated displays or touch sensitive displays include means for electrically connecting traces on a glass layer to a flex cable that can carry signals from a printed circuit board (PCB). In other designs, a PCB or other component including circuitry can be coupled directly to the glass layer. Due to the shrinking size of many electronic devices, design constraints often drive these connections to be as small as possible. At the same time, many electronic devices are subject to large shock loads and must include connections that are robust enough to allow the device to function reliably over an extended period of time.
One method of forming a connection involves the use of a conductive adhesive layer. Conductive particles can be embedded in a resin or adhesive compound and applied to a base substrate using lamination or printing processes. Anisotropic conductive film (ACF) is commonly used as an adhesive layer. Adhesives such as ACF are capable of achieving a very fine pitch, or distance between adjacent conductors. However, ACF is relatively weak when compared to other bonding methods and can create reliability issues when the connection undergoes stress. Another method involves the use of solder or other conductive pastes such as anisotropic conductive paste (ACP). Conductive pastes can provide a mechanical connection stronger than that of conductive films such as ACF. However, conductive pastes are not capable of achieving the same pitch as adhesives. In some cases, conductive pastes and solder can require a separation between conductors that is 5-10 times greater than that of adhesives.
Therefore, what is desired is a method for mechanically and electrically coupling two electronic components that provides a robust mechanical connection similar to ACP and solder while maintaining a fine pitch similar to ACF.